Typically, in a brake-by-wire system, an electric-caliper is disposed at each vehicle wheel. The electric-caliper receives a signal from the Electronic Control Unit (ECU) and presses against brake discs without recourse to a mechanical connection between the driver and vehicle wheels.
Since the brake-by-wire system does not require a mechanical connection between the driver and the vehicle wheels, impedance of the brake pedal is minimized. Accordingly, a pedal simulator is controlled to transmit a proper reaction force of a pedal to the driver, thereby assisting the driver's braking operation.
In the pedal simulator, generating a proper reaction force according to braking conditions of the vehicle is the most important task. Therefore, hysteresis of the reaction force of the pedal should be obtained to reduce the fatigue of the driver's foot in the event of a turn or continuous braking. Also, the controllable range of the reaction force and the response in relation to the control should be sufficient and effective, respectively.